650 D. B. CASTEEL 



The further history of the metamorphosis of the spermatid 

 into the spermatozoon will be deferred until the latter portion 

 of this paper. 



The true mitochondria 



The granular bodies identified as mitochondria are undoubt- 

 edly substances of this nature since they fulfill the more gen- 

 erally accepted criteria, although their "responses to various 

 methods of technique are not always the same throughout the 

 entire history of the germ cells. The general statement may be 

 made that, up to the time the granules aggregate to form the 

 mitochondrial ring, they are relatively inconspicuous features of 

 the cytoplasm, being difficult to resolve in living cells and stain- 

 ing less sharply with those dyes which are accepted as specific, 

 although there is never any doubt of their presence. Evidently 

 some change occurs in their chemical organization at about the 

 time the mitochondrial ring forms. In stages earlier than this 

 the granules are completely dissolved in fixatives containing a 

 large per cent of acetic acid, but the ring itself, although partly 

 dissolved, is usually not entirely obliterated under such treat- 

 ment. Somewhat similar variations in the resistance of mito- 

 chondria to acetic acid have been noted by Regaud ('08) and by 

 others. With Benda's stain, following Meves' solution, the 

 granules of earlier stages show the violet color but faintly, while 

 the ring takes this stain intensely. In living cells janus green 

 and diethylsafranin stain the ring much more intensely than 

 they do the scattered granules of preceding stages. However, 

 osmic acid darkens the granules and the ring with about equal 

 intensity and the same is true of iron haematoxylin following 

 osmic fixation. 



The question of the manner in which the mitochondria of 

 Argas increase in number is extremely difficult to answer. As 

 has already been noted, such an increase probably occurs to 

 some extent throughout the growth of the germ cells, and prob- 

 ably at a rapid rate just before and during the process of matura- 

 tion. While conclusive evidence is not at hand for absolute 

 statements, my material warrants the belief that the addition 



